Does anyone here run a PCIII on their FJR, and if you do, do you also run the cat eliminator plug? I have been running a PCIII for years with no other mods, with the O2 sensor disconnected (this was the recommended configuration from Dynojet). However recently I became aware that they came out with an O2 sensor plug that is nothing but two resistors across the 4 wires. Some have said the adaptation in the FJR ECU does weird things if it senses a sensor missing, even if no code is thrown. The plug does something and fools the ECU into thinking an O2 sensor is there but doing nothing I guess. This was not apparent or known 5 years ago when I fitted the PCIII and I have lost touch with the cranky old hardcore FJR folks since.

The PCIII improved things a lot at the time but lately I've been wondering just what its tiny little brain is doing about the open O2 sensor socket.

Any feedback rumor innuendo or just plain SWAG appreciated. I have a 2007 with the altitude fix updated ECU.

Hi fred. Mine is also a 2007 with the altitude fix. I dont run a PCIII, I have considered it a while ago but it was too expensive (here in Europe at least..), I didn't want any performance improvement only a fix to the lean surge. This summer I got that O2 sensor plug and yes it's basically a plug with two resistors, but it did make a very significant improvement!! if you disconnect the sensor, the bike will give a error because it cannot read any value, mind you the ECU doesn't connect with the sensor in any tecno-USB-like system! it merely reads resistance values which is what the O2 sensor outputs. With the plug the bike doesn't give you the error because it can now read something, only catch is the reading for the sensor is always the same, the ECU is sufficiently idiot not to understand something is out of the ordinary... :-)

What I was told from a friend that recommended it to me, is that the plug resistance values "fool" the ECU in delivering more fuel to the engine in a closed throttle. This has the huge advantage that when opening the throttle the bike will now be much smoother, because there is not an abrupt fuel flow increase. You also notice the bike has less engine braking. In my case it also improved fuel mileage slightly!

It's cheap, so no big risk in trying. But I cannot say how it will work with a PCIII.

Cheers.
V.

Quote:

Originally Posted by fred flintstone

Does anyone here run a PCIII on their FJR, and if you do, do you also run the cat eliminator plug? I have been running a PCIII for years with no other mods, with the O2 sensor disconnected (this was the recommended configuration from Dynojet). However recently I became aware that they came out with an O2 sensor plug that is nothing but two resistors across the 4 wires. Some have said the adaptation in the FJR ECU does weird things if it senses a sensor missing, even if no code is thrown. The plug does something and fools the ECU into thinking an O2 sensor is there but doing nothing I guess. This was not apparent or known 5 years ago when I fitted the PCIII and I have lost touch with the cranky old hardcore FJR folks since.

The PCIII improved things a lot at the time but lately I've been wondering just what its tiny little brain is doing about the open O2 sensor socket.

Any feedback rumor innuendo or just plain SWAG appreciated. I have a 2007 with the altitude fix updated ECU.

Hi fred. Mine is also a 2007 with the altitude fix. I dont run a PCIII, I have considered it a while ago but it was too expensive (here in Europe at least..), I didn't want any performance improvement only a fix to the lean surge. This summer I got that O2 sensor plug and yes it's basically a plug with two resistors, but it did make a very significant improvement!! if you disconnect the sensor, the bike will give a error because it cannot read any value, mind you the ECU doesn't connect with the sensor in any tecno-USB-like system! it merely reads resistance values which is what the O2 sensor outputs. With the plug the bike doesn't give you the error because it can now read something, only catch is the reading for the sensor is always the same, the ECU is sufficiently idiot not to understand something is out of the ordinary... :-)

What I was told from a friend that recommended it to me, is that the plug resistance values "fool" the ECU in delivering more fuel to the engine in a closed throttle. This has the huge advantage that when opening the throttle the bike will now be much smoother, because there is not an abrupt fuel flow increase. You also notice the bike has less engine braking. In my case it also improved fuel mileage slightly!

It's cheap, so no big risk in trying. But I cannot say how it will work with a PCIII.

Cheers.
V.

Hi VascoS,
Yes that lean surge is one of the issues I'd like to fix, it is still there but not as bad with the PCIII. It is interesting that on the Dynojet website they have a map specifically for the euro version with O2 plug and O2 sensor disconnected, the other maps do not mention O2 plug at all but do mention disconnected O2 sensor. I may try the euro map too.

That era Yamaha seemed to really not pay a lot of attention to ECU and software very much. I have had several of their bikes 06-08 and the fuel mapping was not so good. Motors themselves (the metal bits) are brilliant. Also were some final assembly issues but that was not design per se. The altitude problem drove me crazy but they eventually fixed it. Maybe an issue WRT labor vs too many varying emissions regs worldwide who knows.

I fixed mine by twisting the throttle past 20% during significant altitude changes,

That doesn't fix it, it makes it worse. It was really annoying having douchebag service rep types tell me that over and over. It turns out the software only updated ambient pressure every so often, and when you rode aggressively in big mountain terrain it quickly got out of whack very fast. Stalling repeatedly when you'd try to pass or give it some throttle etc. However if you stopped and shut it off sensor would reset and you'd be good to go for another 1000 feet or so. Bike was unrideable where I lived at the time, would ride from 6k ft to 12 k ft often and hard.

About a year later after a lot of back and forth with Yamaha, I got a letter about an updated ECU. Fixed the problem and has not come back.